如何添加Flex 4 Spark List Item自定义属性

Question

I'm trying to make a simple flash application providing interface for taking tests as a high school assignment. One of the requirements is to use an XML file as data source.
Now, having a List component bound to the XML file with questions consisting of data such as question body, question type (ie. single choice, multiple choice, open, image etc.) and possible answers (where applicable), I was wondering if I could add some additional data (and what is the best possible way to do so) to each question upon its transfer to the List component.
I am trying to achieve two main goals with this: firstly, to mark the questions to which an answer has already been given, like with such code in ItemRenderer class:

<s:Label color="{data.color}" text="{data.label}"/>

where data.color would be set whenever the user gives an answer to a question.
Secondly, while at it, I thought of such possibility as a great way to store answers given to particular questions. In this case, the Class of the answer object would have been Object, since there has to be many type of questions (where the answer could also be a Bitmap for example).

This is a question of both how to do it and if it seems a good idea at all (and if no, if there is a better way?), because I am quite new to the whole Flash Builder and Flex thing and I am not really accustomed to all the possibilities and best practices.

Thanks!

Answer 1

It is considered best practice to assign your XML data results to ValueObjects, you could either add additional data directly in the ValueObject class or use another Class to specifically add logic to your VOs, this in order not to mix logic and data within the same class.

If you're not familiar with Flex/FlashBuilder , have a look at the following tutorial, here's a link referring to VOs
http://www.adobe.com/devnet/flex/videotraining/exercises/ex2_08.html#b

Answer 2

I prefer using something like a Presentation Model for each of the items in the list.

The idea is that you compose a class with the XML data (model data) AND the properties that are more germain to the view. In other words, you map the XML data to a higher-level type and push that into the List. Something like this, where label delegates to the model, but color is something you add in your UI layer.

public class QuestionPM {
    private _model:XML;
    public function QuestionPM(model:XML) {
        _model = model;
    }

    public function get label():String { return _model.label; }
    public var color:String;
}